1. The Field of the Invention
The present invention relates to a filter cleaning system for air handlers and, more specifically, to a system for automatically cleaning filters in warm-air furnaces, air conditioners and the like.
2. The Prior Art
In domestic warm-air furnaces, filters are periodically replaced by a new filter or occasionally they are cleaned and replaced. Clogged filters inhibit the full, proper air flow through the heat exchanger and thereby waste energy by poor heat exchanger efficiency and permit damaging overheating of heat exchanger.
Some self-cleaning filters exist; but the systems required are very complex and not directly compatible with warm-air furnaces.
F. Lang (U.S. Pat. No. 3,183,647) teaches a movable nozzle that oscillates across a moving filter element (or elements) to pick up by suction dust particles that have settled on the upstream face of the filter. There is no specific destiny for the dust particles and the general configuration of the device is not clearly compatible with present domestic warm-air furnaces while the present invention provides for specific means of dust disposal and is clearly compatible with present warm-air furnaces.
F. D. Noland (U.S. Pat. No. 4,082,524) teaches a method of cleaning a filter used to remove dust from the exhaust of a grain dryer by a rotating vacuum inlet and disposes the dust into a cleanable chamber. The purpose there and the required structure are different in form and function; the dust pickup moves rather than the filter. That device is not a practical adjunct to domestic warm-air furnaces or similar appliances.
Per Norbach (U.S. Pat. No. 4,296,780) teaches a structure for cleaning a throttling device which consists of a "plurality of fine through passages for conveying air" so that the fine through passages do not get clogged. The dust pickup plenum rotates over a fixed filter while I teach a rotating filter past a fixed pickup plenum. Norbach finally delivers the dust into the main stream while I teach the constant filtering of air, the perpetual cleaning of the filter, and convenient disposal of airborne dust away from the air stream.
W. L. Kinney, Jr. and R. E. Evans, Jr. (U.S. Pat. No. 4,481,021) teach a device with a rotating convoluted drum filter with suction pickups in the valleys of the convolutions of the filter media. There is no indication of method of disposal of dust and the device is not suitable for integration into, or use with, a typical warm-air furnace.
T. J. Retka and G. S. Wylie in an ASME Paper No. 86-GT-126 published by ASME, Journal of Engineering for Gas Turbines and Power, Jan. 1987, Vol. 109, pg. 79-84, describe a pulse-jet self-cleaning air filtration system for gas turbines which blows a blast of high pressure air in reverse direction to clean the filters when excessive pressure drop indicates that the filters are clogged. This is a large complex system that may be appropriate for the large installation described but neither suitable nor compatible with warm-air furnaces.
J. P. Murphy and H. Camplin in ASME paper 88-GT-85 describe a self-cleaning air filtration system for a U.S. Army battle tank which comprises a rotating cylindrical filter with high velocity jets that drive the dust from the upstream face into receiver plenums opposite the high velocity jets which accept and remove the dust. This system uses a cylindrical moving filter which is not readily compatible with the construction of conventional warm-air furnaces while the invention taught herein comprises a flat filter which is more compact and more compatible with conventional warm-air furnaces.